In the debate on whether to charge for content, some sites are moving into the so-called "freemium" model by offering content free and adding services for which they charge.

The premise is that basic content cannot be sold but additional features or functionality do offer such an opportunity. Bloomberg outlines how some sites view their evolution into services as the gateway to revenue generation.

Certainly in an era of commodified content, it is a challenge to find options for which users are willing to pay. The Bloomberg piece suggests that many big firms are betting big on freemium.